To make your crust:
You will need a food processor for this
- Add your rice flour, psyllium husk, salt, tapioca starch, potato starch, and pulse a few times.
- You are going to want to cut your butter up into cubes. I like to quarter mine as it make it easier to pulse.
- Add your butter to your food processor and pulse a few times. You want the butter to still be visible and be around the size of a pea.
- Now, one tablespoon at a time, while you are pulsing your dough, add your water. Once you have added 3 tablespoons, you should see it start to look really crumbly. After 4 tablespoons, it should start to form a ball of dough. If it does not do this with 4 tablespoons, add 1 more and that will do the trick.
- Remove your dough from the food processor and cover in plastic wrap (or an eco-friendly alternative) and flatten into a disc. You will want to then cover it completely and place in the fridge for 1 to 2 hours.
- Once the dough has properly chilled, you will need two pieces of parchment paper. Place the disc between them and begin to roll out your dough to the necessary size of your tart pan. Place the dough into the tart pan, and if you have excess dough hanging off the side of the tart pan, use your rolling pin to roll over the tart pan, It will force the dough to cut off where you want it to.
- Push the dough so that it properly fits into the cracks of you pan. If you have any place that is cracking or has torn, take a piece of the excess dough and just push it on in there.
- Place your tart back into the fridge for twenty minutes and in the mean time make your filling.
To make the filling:
- Take your butter and sugar and cream them together using your beater attachment in your standing mixer. Let this mix for 3-5 minutes and allow it to really come together. If you need to scrape down the sides, do so.
- Add the rest of your ingredients; egg, almond flour, almond extract, and tapioca starch and allow it to mix for 3-5 minutes.
- While this is mixing, turn your oven to 350°F.
- If you have not chopped up your rhubarb stalks, do so now.
Putting it all together:
- Remove your tart shell from the fridge.
- Add your frangipane (the almond mixture) to the tart shell. If you need to, use a spatula to smooth everything out. You want to make sure that you have an even amount of frangipane throughout the entire tart.
- Place your rhubarb on top in the design you want.
- Place your tart in the oven. You are going to bake your tart for 1 hour or until your crust and frangipane filling are a nice golden color.
- Once it is done baking, you will remove from the oven and transfer your tart to a wire rack. Allow it to cool completely.
- I think the best thing for this tart is to then put it in the fridge over night to allow everything to really sit and settle. If you cannot possibly wait, you can go ahead and eat it once it has cooled. If you attempt to cut into it while the tart is still hot, the crust will be more crumbly.